title: Processing of exogenous hepatitis B surface antigen particles for Ld-restricted epitope presentation depends on exogenous beta2-microglobulin.
abstract: Processing of exogenous hepatitis B surface antigen (HBsAg) particles in an endolysosomal compartment generates peptides that bind to the major histocompatibility complex (MHC) class I molecule Ld and are presented to CD8+ cytotoxic T lymphocytes. Surface-associated 'empty' MHC class I molecules associated neither with peptide, nor with beta2-microglobulin (beta2m) are involved in this alternative processing pathway of exogenous antigen for MHC class I-restricted peptide presentation. Here, we demonstrate that internalization of exogenous beta2m is required for endolysosomal generation of presentation-competent, trimeric Ld molecules in cells pulsed with exogenous HBsAg. These data point to a role of endocytosed exogenous beta2m in the endolysosomal assembly of MHC class I molecules that present peptides from endosomally processed, exogenous antigen.
authors.affiliation: Institute for Medical Microbiology and Immunology, University of Ulm, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schirmbeck
authors.forename: S
authors.initials: S
authors.lastname: Thoma
authors.forename: J
authors.initials: J
authors.lastname: Reimann
mesh_terms: D017951:Antigen Presentation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D000939:Epitopes / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D001613:beta 2-Microglobulin / Q000276:immunology*
chemical_list: D000939:Epitopes; D006514:Hepatitis B Surface Antigens; D015395:Histocompatibility Antigens Class I; D001613:beta 2-Microglobulin